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. Author manuscript; available in PMC: 2012 Oct 4.
Published in final edited form as: Biochemistry. 2011 Sep 8;50(39):8392–8406. doi: 10.1021/bi200593m

Figure 2.

Figure 2

The influence of ZhuI on first-ring cyclization specificity in engineered biosynthesis. (A) Combination of the Act MinPKS, KR, ARO/CYC, and CYC proteins from S. coelicolor results in production of the octaketide DMAC. In comparison, when ZhuI and ZhuJ are combined with the Act MinPKS they direct C7–C12 and C5–C14 cyclization of an unreduced octaketide chain to yield TMAC (4). (B) In vitro reconstitution of polyketide biosynthesis using the PKS4 MinPKS from Gibberella fujikuroi results in the production of napthopyrone 6 and PK8 (7). The addition of the C9–C14 cyclases TcmN or WhiE results in the exclusive production of 7. In contrast, the addition of ZhuI directs the regiospecific C7–C12 cyclization of the nonaketide chain to yield a novel polyketide, NonaSEK4 (5). Note that TcmN and WhiE direct two consecutive cyclizations (C9–C14 and C7–C16), whereas ZhuI promotes only a single cyclization event between C7–C12.